Reversed-Polarity Secondary Deformation Structures Near Fault Stepovers
Reversed-Polarity Secondary Deformation Structures Near Fault Stepovers
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断层跨距附近的反极性二次变形结构
DOI：
10.1115/1.4006154
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Shiqing Xu
中科院分区：
文献类型：
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作者：
Y. Ben‐Zion;T. Rockwell;Zheqiang Shi;Shiqing Xu
我们使用数值模拟和实地观察研究了跨越区域的体积变形结构，重点关注破裂段末端附近的小尺度特征，这些特征与表征整个跨越区域的大尺度结构具有相反的极性。反向极性的小尺度结构被解释为产生的逮捕阶段，开始在障碍和传播一定的距离回到破裂段。动态断裂作为对称的双边裂纹扩展，在断裂两端产生相似的（反对称的）结构。相反，破裂的形式主要是单向脉冲产生明显的reversedpolarity结构，只有在故障端的主要传播方向。在加州南部的圣安德烈亚斯系统的走滑断层的几个不同尺度的观测实例说明了反极性次级变形结构的存在。在所示的例子中，相对较小的压力脊只出现在相对较大的伸展阶跃的一侧。这表明至少在某些情况下，频繁的主要是单向破裂，尽管需要多信号观察来区分不同的可能机制。结果有助于推断的能力，从现场观测的持续性行为的地震破裂与个别断层部分。[DOI 10.1115/1.4006154]
We study volumetric deformation structures in stepover regions using numerical simulations and field observations, with a focus on small-scale features near the ends of rupture segments that have opposite-polarity from the larger-scale structures that characterize the overall stepover region. The reversed-polarity small-scale structures are interpreted to be generated by arrest phases that start at the barriers and propagate some distance back into the rupture segment. Dynamic rupture propagating as a symmetric bilateral crack produces similar (anti-symmetric) structures at both rupture ends. In contrast, rupture in the form of a predominantly unidirectional pulse produces pronounced reversedpolarity structures only at the fault end in the dominant propagation direction. Several observational examples at different scales from strike-slip faults of the San Andreas system in southern California illustrate the existence of reversed-polarity secondary deformation structures. In the examples shown, relatively-small pressure-ridges are seen only on one side of relatively-large extensional stepovers. This suggests frequent predominantly unidirectional ruptures in at least some of those cases, although multisignal observations are needed to distinguish between different possible mechanisms. The results contribute to the ability of inferring from field observations on persistent behavior of earthquake ruptures associated with individual fault sections. [DOI: 10.1115/1.4006154]